Great blocks! When adding borders I consider how big I want my quilt to be and I usually base my border strips on measurements taken from inside the quilt. It looks like you have 2 and 4 inch squares in the chain blocks so I might do a 2 inch, 3 inch, 4 inch triple border. When adding multiple borders, it is best to sew the borders together before adding them to the quilt. If you sew the borders on one at a time, you may get waves in the borders as each extra border stretches the last edge a bit. You also need to decide if you want to miter your 3 strip border or use corner stones in each corner which is easier.